Method and apparatus for adjusting an electronic yarn cleaner

ABSTRACT

A method of, and apparatus for, adjusting an electronic yarn cleaner having a yarn feeler mechanism for generating a scanning signal dependent upon the cross-section of a yarn or the like to be cleaned and at least one controllable channel connected with the yarn feeler mechanism for evaluation of the scanning signal and for triggering a yarn cutter mechanism in the event there is present a defective yarn cross-section. For the purpose of automatically adjusting or setting at least one evaluation channel during travel of the yarn there is derived a thickness signal from the scanning signal, the magnitude of which thickness signal represents the yarn thickness determined over a larger section of the yarn. While taking into account the relative cleaning boundary of the evaluation channel this thickness signal is processed into a control signal for the evaluation channel in order to adjust its response threshold in the same sense as the magnitude of the thickness signal.

United States Patent Stutz July 1, 1975 [54] METHOD AN!) APPARATUS FOR 3,758,216 9/1973 Stutz r r 28/64 x ADJUSTING AN ELECTRONIC YARN 3,809,869 5/1974 Gebald .1 235/l5l3 CLEANER P E Ed d J w nmary xammer war we [75] Inventor HaPSrued' Sun! D'ethkon Attorney, Agent, or FirmWerner W Kleeman Switzerland [73] Assignee: Aktiengesellschaft Gebruder Loepfe, [57] ABSTRACT Zurich, Swnzerland A method of, and apparatus for, ad usting an elecl Flled? 28, 1974 tronic yarn cleaner having a yarn feeler mechanism [211 Appl. No: 437,494 for generating a scanning signal dependent upon the cross-section of a yarn or the like to be cleaned and at least one controllable channel connected with the Foreign pp Data yarn feeler mechanism for evaluation of the scanning Feb. 5, 1973 Switzerland 1550/73 signal and for triggering a yarn cutter mechanism in the event there is present a defective yarn cross- [52] US. Cl. 235/1513; 28/64; 73/160; section. For the purpose of automatically adjusting or 328/271 setting at least one evaluation channel during travel of [51] Int. Cl. D02j 1/14; l-[Olj 19/82 the yarn there is derived a thickness signal from the [58] Field of Search 235/l5l.3; 356/238, 200, scanning signal, the magnitude of which thickness sig- 356/159; 28/64; 73/l60; 324/71 R, 6]; 328/27] nal represents the yarn thickness determined over a larger section of the yarn. While taking into account [56] Reterences Cited the relative cleaning boundary of the evaluation chan- U ITE STATES PAT S nel this thickness signal is processed into a control sig- 3 458 912 M969 warm 28/64 nal for the evaluation channel in order to adjust its re- 3594:558 7/197 ijj sponse threshold in the same sense as the magnitude 3,63l,354 12/1971 Wertfeli r 28/64 x of the thickness Signal- 3,73l,069 5/]973 Goto et al.... 235/l5l.3 3,743,707 7/1973 Aihara 28/64 17 Clams Drawmg figures Third Channel Seteclov Second Channel Comparator seecw' 17 e CR 19 18 I CnnlvulSoqnol NR NRI Tronsmmers Reference Vuiue 2i at Transmitter 2 FZ 15 vs v1), v11 1 I Control Chunnelsfirst Channel l E'il? J SE C J o 1 C 5 1 SIWWMHM'SA K2 V B I Amohher gtucmge A Quipul Sloqe n I S" Evaluation \1 l Dev1ce Peeler /-3 TI 11 {K Hood l. d us|vmem You Yam Componsatmn Devtce cur," Tmctmess Snqnol Tmnsmn ler Pl' IT-WFMUL'I 1213 13,892,951

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VC R Controllable 70 EEBjJiIf-iE'IffBIQMIGI 1 VS I Amphfl-er J A so E1 E2 F OP Operational f I Amplifier K I 1 METHOD AND APPARATUS FOR ADJUSTING AN ELECTRONIC YARN CLEANER BACKGROUND OF THE INVENTION The present invention relates to a new and improved method of adjusting an electronic yarn cleaner possessing a yarn feeler mechanism for generating a scanning or feeler signal which id dependent upon the crosssection of the yarn to be cleaned and at least one controllable channel is connected with the yarn feeler mechanism for evaluation of the scanning signal and for triggering a yarn cutter mechanism in the event of a defective cross-section of the yarn, and this invention also pertains to a new and improved construction of apparatus for the performance of the method aspects of this development.

It is to be understood that as employed herein under the expression cross-section" there is to be understood a random local or momentary transverse dimension of the yarn or thread, such as yarn diameter, crosssectional surface area, mass or volume per unit length. In order to differentiate therefrom the hereinafter employed expressions yarn thickness" and thickness signal" relate to values of such transverse dimension determined over a longer yarn section; therefore the term thickness" is not intended to be limited to a predetermined dimension, for instance the diameter.

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide an improved method of, and apparatus for, reliably and accurately adjusting an electronic yarn cleaner.

Another object of this invention aims at simplification of the adjustment operation of an electronic yarn cleaner by at least partially automating such adjustment.

Yet a further significant object of the present invention relates to a new and improved construction of apparatus for adjusting an electronic yarn cleaner which is relatively simple in construction and design, extremely reliable in operation, and not readily subject to breakdown or malfunction.

The invention is based upon the experience that the yarns which are to be cleaned can be grouped together or classified into groups of similar yarns in such a manner that for each group there can be established a uniform cleaning instruction or requirement for the cleaning boundaries dependent upon the cross-section magnitude, for instance the diameter of the yarn or the like. Thus, for instance, cotton yarns, which for otherwise similar properties only can be distinguished by their average or mean diameter or their yarn number, can be grouped together into such type group.

One such uniform cleaning regulation or specification resides, for instance, in the fact that for a group of similar yarns there are applicable the same values for the relative cleaning boundaries, specifically the magnitudes:

C, C/d for the defect of a double yarn or two ply yarn,

D, D/d as the lower diameter boundary for the determination of longer defect locations, and

N, N/d as the lower diameter boundary for short thickened locations (naps) which are to be cut-out.

These magnitudes advantageously constitute adjustment or setting parameters for the yarn cleaner. It is to be understood that reference character d represents the average or mean diameter of the yarn, whereas reference characters C, D and N represent the absolute measured diameter of the boundary error for the individual yarn.

The aforementioned cleaning boundaries can be ascertained for a predetermined group of yarns by carrying out trial runs at one or a few yarns and then can be used without modification for all yarns of the group for the purpose of adjusting or setting the yarn cleaner during operation of the winder or spooler. For the values C, and D, there are generally applicable, however, approximately fixed values, to wit:

C, 1.4 corresponding to an assumption of a circular-shaped cross-section of a double yarn, and

D, 1.2 constituting a value ascertained by experience, whereas N, can fluctuate within wide limits, approximately N,

= 4-l0. This value is for a predetermined group, for instance 7.

Measurement of such values always should occur at the running or traveling yarn and not at the stationary yarn in order to obtain positively derived values. With appropriate construction of the yarn cleaner and its adjustment mechanism it is then necessary to only adjust one time, for a group of similar yarns, the values of C,, D, and N,; for each individual yarn of the group it is then only necessary to further take into account, during the adjustment, the size of its cross-section, for instance the average or mean diameter d. As a result, there is further possible an automatic adjustment, that is to say, once there has been adjusted or set the values of C, D,- and N, for a group, the value of an individual yarn diameter can be determined with the aid of a direct and automatic measurement and automatically processed into a control magnitude and introduced into the yarn cleaner.

This is realized with the inventive method in that for the purpose of automatically adjusting or setting at least one evaluation channel, with the yarn traveling, there is derived from the scanning or feeler signal a thickness signal, the magnitude of which represents the yarn thickness determined over a longer yarn section, and while taking into account the relative or relevant cleaning boundary (C,, D,, N,) of the evaluation channel such thickness signal is processed into a control signal for the evaluation channel, in order to adjust its response threshold in the same direction or sense as the magnitude of the thickness signal.

According to an advantageous embodiment of the inventive method only one thickness signal is derived for the purpose of adjusting an electronic yarn cleaner containing a number of controllable evaluation channels, and from such thickness signal and signals which represent the cleaning boundaries there is simultaneously formed the control signals for all evaluation channels.

If the inventive method is employed in conjunction with an electronic yarn cleaner which, in the absence of any yarn at the yarn feeler mechanism, delivers a base signal which differs from null, however generates a scanning signal when yarn is present at the yarn feeler mechanism, and which scanning signal differs from the base signal by an amount corresponding to the crosssection of the yarn, then advantageously the base signal is compensated, so that there is formed a yarn signal which is representative of the cross-section of the yarn,

and from such yarn signal there is derived the thickness signal.

If, however, the inventive method is employed in conjunction with an electronic yarn cleaner which di rectly delivers a yarn signal representative of the crosssection of the yarn, then such yarn signal, while carrying out a determination over a longer yarn section and, if desired, with amplification thereof, can be directly transformed, that is to say without compensation, into the thickness signal.

The thickness signal can be formed such that it is proportional to the determined yarn thickness, or also such that its magnitude increases, with increasingly determined yarn thickness, by an amount which is less than proportional thereto, for instance, logarithmically.

As already mentioned above, the invention is not only concerned with the aforementioned method as pects but also relates to a new and improved construction of apparatus for the performance of the inventive method at an electronic yarn cleaner, which encompasses a yarn feeler mechanism and an electronic eval' uation mechanism connected therewith. The electronic evaluation mechanism possesses at least one controllable evaluation channel for triggering a yarn cutter or separation mechanism in the event of the presence of a defective crosssection at a yarn which is to be cleaned. According to the invention the apparatus of this development is manifested by the features that there are provided electronic means for the integration as a function of time of a yarn signal, and which yarn signal constitues a local transverse dimension of a yarn section located at the feeler mechanism of the yarn cleaner, for the purpose of generating a thickness signal, the magnitude of which represents the yarn thick ness determined over a longer yarn section with the yarn traveling or running.

. According to a further aspect of the apparatus of this development there is provided for at least one evaluation channel a controllable DC-amplifier channel and a compensation device which cooperates therewith for surpressing the base signal. The compensation device can be constructed as a feedback circuit. of the DC- amplifier channel and can encompass switching means in order to render effectual from time to time the feedback circuit for compensation purposes, as well as means for holding the compensation signal which is formed when the feedback loop is closed.

In the context of the disclosed invention, under the expression DC-amplifier channel there should not only be understood an amplifier channel with a directcurrent voltage amplifier or direct-current amplifier with direct coupling of the amplifier stages, rather also an amplifier channel which functions in the manner of a direct-current voltage amplifier or direct-current amplifier, without its stages being directly coupled, as such will be discussed more fully hereinafter in conjunction with the first exemplary embodiment and the drawings.

According to a further construction of the inventive apparatus such possesses a switching circuit which, with the yarn traveling, is actuated by a scanning or feeler signal derived from the yarn feeler mechanism and thus brings into operation electronic means for the integration and amplification of a yarn signal. According to a different, advantageous physical construction, the inventive apparatus can be equipped with a servo circuit which encompasses a comparator, the one input of which has delivered thereto a thickness signal deter mined timewise i.e. as a function of time, a potentiometer. at which there is applied a constant direct-current voltage and the tap of which is coupled with the other input of the comparator, as well as a reversible adjustment or setting motor which can be connected with the output of the comparator and which acts upon the tap, wherein the thickness signal, after completion of the balancing of the input signal of the comparator, is present at the tap of the potentiometer in the form of a constant direct-current voltage.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 schematically illustrates a first exemplary embodiment of installation equipped with an apparatus designed according to the teachings of the invention and incorporating an electronic evaluation device and a feeler head of an electronic multi-channel yarn cleaner as well as illustrating the essential components of the inventive apparatus in the form of an electronic thickness signal transmitter, an electronic regulation device and a reference value transmitter;

FIG. 2 is a detailed block circuit diagram of the essential function circuits of the evaluation device depicted in FIG. 1;

FIG. 3 is a detailed circuit diagram of the thickness signal transmitter or generator depicted in FIG. 1;

FIG. 4 is a detailed block circuit diagram of the electronic regulation device depicted in FIG. 1',

FIG, 5 schematically illustrates a variant construction of inventive apparatus with separate electronic channels at the thickness signal transmitter and at the regulation device for the parallel processing of the signals delivered from the evaluation device;

FIG. 6 illustrates the block circuit diagram a further exemplary embodiment of the inventive apparatus in conjunction with an electronic evaluation device modified in relation to that shown in FIGS. 1 to 4',

FIG. 7 is a schematic circuit diagram of the electronic evaluation device of the yarn cleaner of the installation or system depicted in FIG. 6;

FIG. 8a is a block circuit diagram of the thickness signal transmitter of the system depicted in FIG. 6;

FIG. 8b is a circuit diagram of the controllable amplifier channel of the system depicted in FIG. 6;

FIG. 9a is a schematic circuit diagram of the associated regulation device of the system depicted in FIG.

FIG. 9b is a circuit diagram of one of the circuits of such device;

FIG. 10 illustrates a further exemplary embodiment encompassing circuits for compensating a base signal contained in the scanning signal delivered by the electronic yarn cleaner;

FIG. 11 are graphs portraying voltages which appear in the apparatus of FIG. 10 upon carrying out an adjustment operation and upon triggering the cutting operation;

FIG. 12 is a further embodiment which presupposes that there can be directly derived from the electronic yarn cleaner a yarn signal free of a base signal; and

FIGS. 13 and 14 respectively show a modified evaluation device and a modified amplifier channel of a thickness signal transmitter which can be used in place of the corresponding circuit arrangements of FIGS. 6 and 80 respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Description of FIG. 1

According to the showing of FIG. I the electronic evaluation device 1 encompasses three parallel controllable signal channels K1, K2, K3. The scanner or feeler head 3 encompasses a yarn cutter or separation mechanism 4 and for instance an optoelectrical yarn feeler or scanner mechanism 5, the output of which is coupled with the signal inputs of the three previously mentioned signal channels K1, K2 and K3 and which delivers a signal S representative or characteristic of the yarn diameter d. Each of the signal channels K1, K2 and K3 has operatively associated therewith a control channel S1, S2, and S3 respectively, to which there is delivered a control signal VC, VD and VN respectively, and which delivers at a control input of the associated signal channel a derived control signal C, D' and N respectively. The outputs of the signal channels K1, K2 and K3 are connected with an output stage T1, the output of which is coupled with the yarn cutter mechanism 4, as shown. Thus, each series connection of a control channel, e.g. S1, a signal channel e.g. K1, and output stage Tl forms a controllable evaluation channel.

The electronic evaluation device 1 serves the purpose of evaluating the electrical scanning or feeler signals S generated by the yarn feeler or scanning mechanism 5 during scanning of a running or traveling yarn 11 and upon the occurrence of certain impermissible yarn defects in each case generating a cutting or separation pulse T by means of which the yarn cutter mechanism 4 is activated, so that it cuts or severs the yarn 11.

The electronic thickness signal transmitter or generator 2 encompasses, as the central component, a controllable amplifier channel 7 which, as will be explained more fully hereinafter, functions as a direct currentamplifier channel. This amplifier channel possesses three inputs, namely a signal input A, a control input B and a compensation input K, as well as two outputs El and E2. The signal input A is connected to the output of the yarn feeler mechanism 5, which delivers the scanning or feeler signal S. A first channel selector 6 serves the purpose of selecting in each instance one of the derived control signals C', D, N and to deliver such to the control input B. Cooperating with the amplifier channel 7 is a compensation device or mechanism 9 which can be randomly connected therewith, this compensation device 9 being connected between the first output E1 of the amplifier channel 7 and the compensation input K and functions as a feedback circuit, so that there is possible compensation of a DC- base signal of the scanning signal S delivered by the yarn feeler mechanism 5 when the yarn is not present. In this way it is possible to render ineffectual the drift which is produced by the optical and optoelectrical components at the yarn feeler mechanism 5 and similarly the drift generated at the amplifier channel 7. At the output E2 of the amplifier channel 7 there appears the yarn signal F freed of the base signal.

Further, at the second output E2 of the amplifier channel 7 there are coupled two null adjacent circuits l2 and 13 which are separated from one another, and

which circuits serve for the automatic actuation from time to time of the compensation device 9, as such will be more fully developed in conjunction with the description of FIG. 3. Moreover, the thickness signal transmitter 2 encompasses an integrationand storage circuit 14 coupled with the second output E2 of the amplifier channel 7 and an indicator device or mecha nism 8, for instance an indicator instrument, connected with its output O, which renders possible continual monitoring of the mode of operation of the thickness signal transmitter 2 by visual observation.

The thickness signal transmitter or generator 2 serves the purpose of delivering an output signal O, which corresponds to the magnitude, determined as a function of time, of the cross-section of a yarn ll inserted into the feeler or scanner head 3. For this purpose there is connected in parallel with the amplifier channel 7 via the channel selector 6 in each case one of the signal channels [(1, K2, K3 of the evaluation device 1 and such amplifier channel 6 is constructed such that its gain always corresponds to the gain of the momentarily parallel connected signal channel. Since the signal channels K1, K2 and K3 have different gain there is provided at the amplifier channel 7 a gain regulator or control (not shown) which can be simultaneously switched with the channel selector 6 via a mechanical connection Fl, so that at the momentarily selected signal channel K1, K2 or K3 respectively and at the amplifier channel 7 there prevails the same gain for each adjustment or setting of the channel selector 6.

The compensation device 9 serves the purpose of compensating to null the direct-current voltage signal, which is delivered by the yarn feeler mechanism 5 in the absence of the yarn or after lifting-out the yarn respectively. For facilitating and automating the compensation there are provided the null setting or adjustment circuits or devices 12 and 13, which from time to time bring about a connection of the compensation device 9 with the amplifier channel 7. With the yarn 11 running or moving the compensation operation also can be randomly activated, as desired, or also automatically at periodically repeated intervals. Between the compensation intervals and after the reinsertion of the yarn at the yarn feeler head or sensor 3 there is undertaken the measurement of the yarn cross-section by the yarn thickness signal transmitter 2. This will be likewise more fully explained in conjunction with the discussion of FIG. 2 as will also the function of the holding circuit 30.

Between the output 0 of the integrationand storage circuit 14 of the thickness signal transmitter 2 and the inputs of the control channels S1, S2, S3 of the evaluation device 1 there is connected a regulation mechanism or device 15. Such encompasses as the input circuit a comparator 16, which according to the showing of FIG. 4 possesses a thickness signal input I, which is coupled with the output Q of the thickness signal transmitter 2, and a reference value input S. A reference value transmitter I7 equipped with three adjustment or setting devices CR, DR, NR, which deliver the reference value voltages CR, DR, NR, is connected via a second channel selector 18 with the reference value input S of the comparator 16. The scales of the adjustment devices CR, DR, NR are advantageously calibrated in values of the relative cleaning boundaries C D N,. Thus, associated with a predetermined adjusted or set value of C,- is a predetermined value of CR. Furthermore, there is provided a third channel selector 19 and three control signal transmitters 21, 22, 23, of which always one is influenced by the comparator 16 depending upon the adjustment of the channel selector 19. The control signal transmitters 21, 22, 23 are continuously effectual by means of the control signals VC, VD, VN at the control channels S1, S2, S3. The second channel selector 18 is coupled with the first channel selector 6 of the thickness signal transmitter 2 through the agency of a mechanical connection F2 and this is also the case for the third channel selector 19 through the agency of a connection F3, so that in each instance there is formed a closed regulation circuit, for instance for the C-channel starting from the control channel 51 (control signal C) via the electronic thickness signal transmitter 2, the comparator 16, the channel selector 19 and the control signal transmitter 21 back to the control channel S1.

At this point there will be explained, by way of example, the use and mode of operation of the apparatus depicted in FIG. 1. Initially there are adjusted or set the values for the adjustment or setting parameters, for instance C, 1.4, D 1.2, and N, 8 at the reference value transmitter 17 and with the aid of the channel selectors 6, 18 and 19 there is selected the C-channel. Thereafter, and with the thread or yarn 11 not inserted into the feeler head 3 the thickness signal transmitter 2 is compensated to null; the output signal of the integrationand storage circuit 14 then has the value null which is approximately constant as a function of time, Next the yarn is inserted into the feeler or scanner head 3 and as a result thereof the compensation device 9 is automatically switched-off, as such will be more fully explained hereinafter in conjunction with the discussion of FIG. 2. Directly after the insertion of the yarn 11 there appears at the output of the integrationand storage circuit 14 a thickness signal O, which represents the magnitude of the diameter d of the yarn determined as a function of time.

In the comparator 16 the thickness signal is compared with the reference value signal CR' emanating from the adjustment device CR of the reference value transmitter 17 and the difference CR Q is formed. This difference is delivered to the control signal transmitter or generator 21 which forms therefrom a control signal VC. Now since this signal is a direct-current voltage signal, but the signal channel Kl, as such will be explained in conjunction with FIG. 3, must be controlled by a pulse voltage, the direct-current voltage-control signal VC is transformed at the control channel S1 of the evaluation device 1 into a pulse control signal C, the pulse duration of which, for constant pulse frequency, is modulated as a function of the magnitude of the control signal VC. The pulse control signal C now is effective on the one hand upon the signal channel Kl of the evaluation device 1 and, on the other hand, upon the amplifier channel 7 of the thickness signal generator or transmitter 2 in the sense that the thickness signal Q is regulated to the value of the reference signal CR from the reference value transmitter or generator 17. This will be further explained in terms ofa numeri cal example. It is assumed that the output signal 0' i constituted by a direct-current voltage signal of a ma nitude of 14 volts, and which output signal appear when there has been reached at the evaluation device I the fixed response threshold of the C-channel and there has been triggered a separation or cutting pulse T. This means that the thickness signal O, which corresponds to the average or mean yarn diameter d, with correct adjustment of the C-channel, must possess a magnitude of 14 volts: 1.4 10 volts; this is thus the reference value which is represented by the signal CR and to which there must be regulated the signal 0' which is present when the yarn or thread is introduced into the feeler head 3.

Let it be assumed that the output signal Q',, which is present prior to regulation has the magnitude 12 volts and the associated control voltage VC,, is 6 volts. Then, the comparator delivers a regulation voltage of (10 12 volts) 2 volts at the C-control signal generator 21; consequently, the magnitude of the control signal VC is reduced from 6 volts to 5 volts and in a corre sponding relationship also the control signal C. Hence, the gain of the C-signal channel Kl correspondingly drops and that of the parallel connected amplifier channel 7 in a ratio 6:5 so that the output signal is reduced in the same ratio or relationship and is regulated to the final value Q, 10 volts, whereby the adjustment of the C-channel is completed.

The adjustment of the D-channel and the N-channel takes place thereafter in the just described manner after removed compensation of the thickness signal transmitter 2.

Description of FIG. 2

In FIG. 2 there is illustrated in block circuit diagram the Construction of the evaluation device 1. This device contains three channels, namely a C-channel (double yarn channel) an N-channel (nap channel or short de fect channel) and a D-channel, as well as a common output stage T1 connected to the outputs of such channels, and which output stage T1 is equipped with a threshold value discriminator DI. Each of these channels encompasses one of the control channels S1, S2, S3 and one of the signal channels K1, K2, K3. The signal channels, the gain of which is different, serve for the evaluation of the scanning or feeler signal S delivered from the yarn feeler mechanism 5 (FIG. 1), and which scanning signal is delivered to a signal amplifier SA common to all channels. Each time when, with the yarn 11 running, the output signal of one of such channels reaches the response threshold of the threshold value discriminator DI of the output stage Tl, such is triggered and produces a cutting or separation pulse T, by means of which the yarn cutter device or cutter 4 (FIG. 1) is activated in order to eliminate any disturb ing yarn defect. The control voltages VC, VD, VN, which determine the gain of the signal channels K1, K2 and K3 and thus the minimum size of the yarn defect to be overcome, are delivered from the control signal transmitters 21, 22, 23, as best seen by referring to FIGS. 1 and 4. The gain of each signal channel is proportional to the size or magnitude of the associated controi signal.

At this point there will be given a more precise description of the electronic circuits which have been portrayed in FIG. 2. Since the channels of the evaluatimi tlc'VlCE l for the most part are the same as regards 1 asic construction, there will be initially described v he C-channel.

, nmion pulse generator PG is provided for the three control channels S1, S2, S3, this pulse generator PG generating a sequence of square wave pulses with a pulse frequency of, for instance, 30 KHZ. At one input of a pulse duration modulator PDM there is delivered the pulses generated by the pulse generator PG and at the other input of which there is delivered the control voltage VC. The duration of the pulses which appear at the output of the pulse duration modulator PDM is proportional to the control voltage VC. These pulses are delivered to a control amplifier CA, which delivers at its output the derived control signal C in the form of a sequence of square wave pulses.

Operatively associated with the three signal channels K1, K2, and K3 is the signal amplifier SA, to which there is supplied the scanning signal S delivered from the yarn feeler mechanism (FIG. 1).

The signal channel K1 contains as the modulation stage a pulse amplitude modulator PAM l, the one input of which is coupled with the output of the signal amplifier SA and the other input of which has delivered thereto the control signal C At the pulse amplitude modulator PAM 1 there takes place a multiplicative mixing of the derived control signal C and the amplified scanning signal S. Accordingly, there appears at the output of the pulse amplitude modulator PAM l a pulse which, with fixed adjusted control voltage VC, is modulated by the amplitude of the scanning signal S. The output pulse from the pulse amplitude modulator PAM l is demodulated at the successively arranged demodulator DEM l, and the demodulated signal is delivered to the output or terminal amplifier EAl. Up to this point the three channels possess the same construction, however they have different gain and different output stages. The output stage of the C-channel encompasses a low-pass filter TP which only passes signals of relatively long duration, which correspond to a length of the running yarn of a number of decimeters (dm). The one input of the already mentioned threshold value dis criminator D] which is common to all channels is connected to the low-pass filter TP. The output of the threshold value discriminator is coupled with the cutter or separation device 4 (FIG. 1).

The output stage of the D-channel encompasses a length measuring circuit LM. This length measuring circuit LM delivers a length signal, which indicates the length of a yarn section, the thickness of which has exceeded a predetermined value determined by the con trol voltage VD. The length scale of the length measuring circuit LM can be controlled with the aid of a control voltage L, which is delivered to a second input of such circuit.

For the N-channel and the D-channel there is provided a common combination stage DN, both of the inputs of which have delivered thereto the output signals of the N-channel and the D-channel respectively. At the combination stage DN there occurs a functional coupling, for instance an addition or multiplication of the output signals delivered by the aforementioned channels. The combination signal generated by the combination stage DN is delivered to a second input of the threshold value discriminator D], which for instance can be constructed as a monostable multivibrator,

Description of FIG. 3

The components of the electronic thickness signal transmitter or generator 2 have already been described briefly in conjunction with FIG. 1. In FlG. 3 there is shown a circuit of the essential components of the thickness signal transmitter 2 in the form of a detailed block circuit diagram. The channel selector 6 is equipped with a threeway reversing switch KS, the fixed contacts of which are connected with a respective one of the outputs of the control channels S1, S2, S3 of the evaluation device 1. The amplifier channel 7 contains as the input stage a signal differentiation amplifier SD equipped with the signal input A and the compensation input K. At the output E1 of the differential amplifier SD there is coupled one input of a pulse amplitude modulation stage PAM 2, the control input B of which is electrically coupled with the switching arm or wiper (not particularly referenced) of the reversing switch KS, so that depending upon the position thereof one of the pulsed control signals C D, N will be delivered to the control input B. At the output of the modulation stage PAM 2 there is connected a demodulation stage DEM 2 and at such a switchable output or terminal amplifier stage EA2. Such contains a not particularly illustrated reversing switch device, which is coupled by a suitable schematically depicted mechanical element Pl F1 the threeway reversing switch KS, so that as already mentioned, the gain existing at the amplifier channel 7, for each position of the reversing K switch KS, corresponds to the gain which exists at the associated signal channel of the evaluation device 1. According to the exemplary embodiment under discussion, the amplifier channel 7, owing to the mixing of the control signal with the output signal of the signal differential amplifier SD at the modulation stage PAM 2 and the subsequent demodulation carried out at the demodulation stage DEM 2, has the action of a DC-amplifier channel.

Between the output E1 of the differential amplifier SD and its compensation input K there is arranged the compensation device 9 which serves the purpose of compensating the DC-voltage components of the scanning signal S generated by the yarn feeler mechanism 5 when the yarn is not present. This is advantageous since the signal peak of the DC-voltage components normally is greater by a multiple than the components of the scanning signal S generated by the yarn 11. The compensation device 9 which is connected in the form of a feedback loop contains an amplifier stage RA, a holding capacitor HC and an impedance converter stage IS, the input of which is equipped with a fieldeffect transistor FET, the gate of which is coupled with the one terminal of the holding capacitor HC. Furthermore, there are provided between the output of the amplifier RA and the one terminal of the capacitor l-lC two parallel arranged working contacts G and H' of relays G and H respectively, of the circuits l2 and 13. The amplifier stage RA should possess a high voltage gain, for instance 1000. There should be used a highgrade capacitor HC in order to be able to hold for as long as possible without any appreciable decay the feedback voltage delivered thereto by the amplifier stage RA upon closing one of the contacts G, H, and which voltage should be retained by the capacitor after opening such contact. The impedance converter stage 18 which is equipped with the field-effect transistor FET, owing to the extreme high input resistance, likewise prevents a drain of the charge which is present at the holding capacitor HC. The feedback loop 9' delivers to the compensation input K of the signal differential amplifier SD a compensation voltage K and thus brings about a practically complete compensation of the DC-voltage components of the signal S which appear at the output of the signal differential amplifier SD.

The starting-null adjustment circuit 13 encompasses a rectifier bridge BR, a Zener diode ZD and relay H, the winding of which is connected in series with the Zener diode via the one diagonal of the bridge. The other diagonal of the bridge has delivered thereto the output voltage from the second output E2 of the ampli fier channel 7. Now if this output voltage exceeds the Zener voltage of the diode ZD, as such is the case after switching-in the thickness signal transmitter 2, then a current flows through such diode and the winding of the relay H, so that its work contact H is actuated and so forth. as such has been described above.

The cooperating-null adjustment circuit 12 consists of a series circuit incorporating a Schmitt trigger SCH, a phase inverter Pl, a first monostable switching or tripping element M], a second monostable switching or tripping element M2, and the winding of relay G. The Schmitt trigger SCH is connected to the second output E2 of the amplifier channel 7.

During insertion and likewise during the removal of the yarn 11 there prevail at the feeler or scanner head 5 scanning signals with steep transitions, which mark or denote the insertion and removal of the yarn, Due to the transition signals there is automatically actuated the operating-null adjustment circuit 12 in such a way that it brings into operation the compensation device 9 during the intervals when the yarn is located externally of the feeler or scanner head 5. Consequently, in these intervals or time periods the output signal of the amplifier channel 7 is compensated each time exactly to null.

The integration and storage circuit 14 encompasses two components: the working or work circuit SCH. M3, M4 and R and the effective circuit DA, R and INT which, in a narrower sense, functions as the integrating and holding stage. The work circuit contains, apart from the already mentioned Schmitt trigger SCH, which at the same time also belongs to the null adjustment circuit 12, the series connected two monostable switching or tripping elements M3 and M4 and the winding of the relay R. The differential amplifier DA of the effective circuit is connected in series with the integrator INT, the output of which is coupled with the indicator device 8 and with the one input of the differential amplifier DA, as shown. The input of the integrator INT is short-circuited as long as the relay R is without current and its rest contact R is closed.

The second input of the differential amplifier DA is connected with the second output E2 of the amplifier channel 7.

The mode of operation of the switching circuits l2, l3 and 14 is as follows: shortly after switchingin the apparatus the amplifier channel 7 is in a state of saturation and has a relatively high output DC-voltage. As a result the relay H of the startingnull adjustment circuit 13 is triggered and through closing of the contact H actuates the compensation device 9, and specifically for such length of time until the output voltage of the amplifier channel 7 has dropped beneath a prescribed value. The circuit 13 then again switches-off the cornpensation device 9. Thereafter the operating-null adjustment circuit 12 assumes the function of switching on and switching-off the compensation device 9 in that, during liftingout of the thread or yarn from the feeler head 5. there appears at the output of the amplifier channel 7 a voltage surge, by means of which, via the circuit 12, the relay G is triggered and its contact G is closed and remains closed as long as the monostable switching element M2 is in its work condition or state. During the time when the contact G is closed the output voltage at the outputs El and E2 of the amplifier channel 7 is compensated to null. The monostable switching element M1 prevents an attraction or energization of the relay G already before the voltage at the output E2 has reached its minimum.

The integrationand storage circuit 14 brings about a timewise integration, i.e. an integration as a function of time of the DC-voltage signal F appearing at the output E2 of the amplifier channel 7 during each of the measuring intervals that is to say, the periods when the yarn has been inserted into the feeler head 5 and storage of the integrated signal during the subsequent interval in which the output signal of the amplifier channel 7 is null.

Description of FIG. 4

In FIG. 4 there is illustrated, apart from the reference value transmitter or generator 17, the construction of the regulation device 15.

The comparator l6 encompasses the differential amplifier DA, the positive signal input of which represents the reference value input S and the negative input of which represents the thickness signal input I. The second channel selector l8 and the third channel selector 1), just as was the case for the first channel selector 6, also encompasses a respective threeway reversing switch. The adjustment devices CR, DR, NR of the reference value transmitter 17 can be equipped in each case with a potentiometer, at which there is applied a fixed voltage and at the tap of which there can be taken-off or removed the reference value voltages CR, DR, NR which determine the reference value.

Each of the three control signal transmitters 21, 22, 23 is equipped with a four-stage binary or dual counter Z1, Z2, Z3 for forwards and backwards counting operations and functioning as an analog-digital converter, and each of which possesses three inputs, namely a counting pulse input EC, a counting direction input ER and an enabling input EN, as well as four outputs Al to A4. There can be employed, for instance, counters of the type available under the commercial trade designation. Type Ser. No. 74l90 from the well known firm, Texas Instruments, Inc.

A counting pulse generator 24 which can be constructed as an astable multivibrator and delivering a pulse frequency of, for instance, 1 Hz is coupled with its output with the inputs EC of the counters Z1, Z2, Z3, whereas the output of the comparator 16 is connected with the inputs ER of the counters.

At the output of one of each control signal transmitters 21, 22, 23 there is present a direct-current voltage as long as there no counting pulses arrive, and which direct-current voltage corresponds to the control voltage, for instance to VC, for which the output signal O, which is produced from a yarn with a uniform diameter, corresponds to the reference value, for instance CR.

Furthermore, at the output circuit of the comparator 16 there is present a relay M with the work contact M. by means of which, upon closing the switching arm of the channel selector 19, there is delivered a fixed positive voltage +V. That counter, for instance counter Z1, which receives via the channel selector 18 the positive voltage +V at the input EN, begins to count. Now if the actual value represented by the thickness signal is smaller than the reference voltage delivered by the reference value transmitter 17, then a positive signal appears at the output of the comparator I6 and the counter Z1 begins to count in forward direction. After the first counting pulse from the pulse generator 24 there appears at output A1 a positive voltage, after the second counting pulse there appears at the output A2 a positive voltage and so forth, as such is well known in the electronics art. The value of the resistances of the resistors R1 to R5 are chosen such that the changes of the control voltage VC which are brought about by the counting pulses corresponds to the number of counting pulses. For instance, each counting pulse brings about a change of the control voltage by 1/15 volt, so that pulses bring about a change of 1 volt. Owing to this change the magnitude of the thickness signal 0 increases until there is attained the reference voltage which has been adjusted or set at the adjustment device CR. Then the comparator l6 delivers the signal null and the counter stops counting, since the relay M is de-energized and the contact M' is opened.

If the value of Q is greater than the reference value CR, then the counter 21 counts backwards and the control voltage VC drops until the value of 0 reaches the reference value.

In corresponding manner there is undertaken the adjustment of the other channels in each case after switching the channel selectors 6, 18, I9 and renewed compensation of the base signal at the amplifier channel 7, with the result that the adjustment or setting operation is completed.

Description of FIG. 5

In the apparatus construction depicted in FIG. 5, there have been employed the same reference characters as such have been used in FIG. I for the same components; this is especially the case for the evaluation device I, the yarn feeler or scanner mechanism 5, the reference value transmitter 17 and the control voltage or signal transmitters 21, 22 and 23. The apparatus of this embodiment possesses a modified construction, however, in that there are provided three thickness signal transmitters 2C, 2D, 2N, and at the regulation device 25 there are provided three comparators 16C, 16D, 16N which together with the control signal transmitters 21, 22, 23, form three complete parallel channels for the processing in each case of one of the control signals C, D', N and the scanning signal S. The channel selectors 6, I8 and 19, required for the embodiment of FIG. I and their connections F1, F2, F3, are thus superfluous.

Each of the thickness signal transmitters or generators 2C, 2D, 2N of FIG. 5 encompasses the same components as the thickness signal transmitter 2 of FIGS. 1 and 3, however without the reversing switch 6 and the not-illustrated switching mechanism connected therewith via the connection F] at the output amplifier EA2 (FIG. 3). It is to be however mentioned that each of the corresponding output amplifiers at the thickness signal transmitters 2C, 2D, 2N possess a different gain, which can be adjusted in accordance with the gain of the associated one of the signal channels K1, K2, K3 at the evaluation device 1.

Each of the comparators 16C, 16D, 16N is connected with its two inputs at one of the thickness signal transmitters 2C, 2D, 2N and at the associated one of the adjustment devices CR, DR, NR of the reference value transmitter 17, which can be constructed like the reference value transmitter I7 of the embodiment of FIG. I. The output of each comparator is directly con nected with the input of one of the control signal transmitters 21, 22, 23, which deliver the control voltages VC, VD, VN to the associated control channels of the evaluation device I, as such has already been described in detail in conjunction with the description of FIGS. 1 and 4.

The construction of the apparatus according to FIG. 5 renders possible a simultaneous parallel regulation or control of the three channels of the evaluation device I without switching channel selectors, as such was required with the embodiment of FIG. I. Moreover, the mode of operation of the three channel device according to FIG. 5 however corresponds to that of the single channel device according to FIG. I, so that it is believed to be unnecessary to provide any further detailed description thereof at this point.

Description of FIG. 6

The installation or system depicted in this Figure, just as was the case for the embodiment of FIG. I, also encompasses a yarn feeler or sensing mechanism 5 and an electronic evaluation device 10 of an electronic yarn cleaner and furthermore a thickness signal transmitter 20, a reference value transmitter 17 and a regulation device 30 as components of the inventive apparatus for the adjustment or setting of the yarn cleaner.

Here also the evaluation device 10, like that illustrated in FIG. 2, encompasses three channels, which however as actual direct-current amplifier channels possess a simplified construction. The thickness signal transmitter 20, like the one depicted in FIGS. 1 and 3, here also contains only one amplifier channel 7 (FIG. 8b), however no channel selector. The reference value transmitter I7 can be constructed in the same manner as has been disclosed in conjunction with the description of FIGS. 1 to 4. This is also so for the comparator 16 of the regulation device 30 and the control signal transmitter 21 of the C-channel, whereas the control signal transmitters 26 and 27 of the D-channel and the N-channel are basically of different construction and also not connected to the comparator I6, rather directly controlled from the reference value transmitter 17. Therefore, there are missing the channel selectors I8 and 19 of the regulation device which were provided for the embodiment of FIG. 1.

The installation depicted in FIG. 6 basically differs in its mode of operation from the installation illustrated in FIGS. 1 to 5 in that for regulation purposes there is only employed a single one of the control signals, namely the control signal C. Accordingly, the regulation device 30 is constructed such that after having undertaken an adjustment of prescribed reference values for the relative or relevant cleaning boundaries C,, D, and N at the adjustment devices CR, DR. NR, the control voltages VC, VD, and VN are only still influenced by the derived control signal C in such a manner that the magnitudes VD, VN are regulated proportional to the magnitude VC. This regulation technique is based upon the experience mentioned at the outset of this disclosure that with similar yarns there can be assumed the same values for the relative cleaning boundaries, s0

that then also the ratios DJC and N /C for such yarns are the same.

Description of FIG. 7

The simplified electronic evaluation device 10 again contains. just as was the case for the construction depicted in FIG. 2, three channels, namely a C-channel, a Dchannel and an N-channel, and an output stage Tl connected with such channels.

There will be initially described the construction of the C-channel. Such contains a controllable directcurrent amplifier SVl, the one input of which is connected to a signal amplifier SA which is common to all channels. The control input of the controllable directcurrent amplifier SVl is coupled via a pre-resistor RC with the input for the control voltage VC which generates a control current flowing through the pre-resistor RC. Suitable as the controllable direct-current amplifier there can be used, for instance, an operational amplifier of the commercially available Type CA 3080 of RCA Corporation, or Type MC 1594L of Motorola Corporation. Connected with the input for the control voltage VC is a further pre-resistor RC1, at the free end of which there can be tapped-off the derived control signal C for the thickness signal transmitter 20.

The D-channel and the N-channel are of similar construction, however there is missing thereat a second pre-resistor for tapping-off control signals D and N which are not required in this case Also the gain provided at the channels is different, as such has already been disclosed previously in conjunction with the description of the embodiment depicted in FIGS. 1 and 4. The output stage Tl can be correspondingly constructed as that described in conjunction with the structure considered with reference to FIG. 2.

Description of FIGS. 80 and 8b According to the showing of FIG. 8a, the electronic thickness signal transmitter or generator 20 contains a controllable amplifier channel 7, a compensation device 9, two null adjustment circuits 12. 13 and an integrationand storage circuit 14, which are constructed and coupled with one another in the same manner as such has already been disclosed in conjunction with the description of FIGS. 1 and 3. As already mentioned, in this case there is not provided the channel selector 6 of FIG. I; the derived control signal C is directly delivered to the control input B of the amplifier channel 7. In the same manner as for the C-channel of the electronic evaluation device 10 there is provided at the arnplifier channel 7 a controllable direct-current amplifier SVZ, which is preferably of the same type as the amplifier SVl. The direct current amplifier 5V2 is provided in place of the modulation stage PAMZ and the demodulator DEMZ of the arrangement of FIG. 3. The output or terminal amplifier EAZ of FIG. 8b does not require any reversing switch device as was the case for the corresponding output amplifier of FIG. 3, since there is not necessary any channel switching. However, othervv for the dimensioning and design of the amplifier Chill] nel 7 there is applicable the guidelines which s are given previously in conjunction with the disclosur, FIGS. 1 to 4. At the output of the output amplifitr EAZ, there appears the yarn signal F which is free of the base signal.

Description of FIGS. 9a and 9b The C-channel of the regulation device 30, which extends over the comparator l6 and the control signal generator 21, is constructed like the C-channel of the arrangement of FIG. 4, only there is missing the channel selectors 18 and 19. The control signal generator or transmitter 26 of the D-channel, which produces the control voltage VD. encompasses as the input stage a divider or dividing element 28, the one input (dividend) of which is connected with the adjustment device DR and the other input (divisor) is connected with the adjustment device CR. Connected with the output of the dividing or divider element 28 is the one inni of a controllable amplifier SVD, the control input of which is connected via a resistor R6 with the output of the control signal transmitter 21.

The divider element 28 delivers an output voltage corresponding to the quotient of the reference value voltages DR and CR delivered by the reference value transmitter 17. This quotient is multiplied by the control voltage VC at the controllable amplifier SVD, so that the output voltage assumes the value:

VD (DRlCR') VC Now since DR and CR are fixed adjusted magnitudes and its quotient is a constant c it is possible to rewrite the aforementioned equation as:

VD c, VC

The Nchannel of the regulation device 30 is correspondingly constructed as the already described D- channel and encompasses a dividing or divider element 29, a controllable amplifier SVN and a resistor R7. It delivers an output voltage or, if rewritten with a second constant this equation can be expressed as:

vN 0 I vc Accordingly, the ratio of the control voltages VC, VD. and VN are constant with regard to one another. as long as the adjustment at the reference value transmitter l7 and the reference value signals delivered thereby remain unchanged.

Divider element 28, and likewise the divider element 29, according to the showing of FIGv 9b consists of an operational amplifier 0V and a feedback circuit thereof, in which there is arranged a controllable arn plifier SV. The reference voltage DR is delivered to the positive input of the operational amplifier 0V and the reference voltage CR to the control input of the controllable amplifier SV. The output signal of the operational amplifier OV represents the quotient Di U/CR of the reference voltages delivered thereto.

Suitable as the controllable amplifier SV there can be used the commercially available Type CA 3080 of RCA Corporation or Type MV l594L of Motorola Corporation Description of FIG. 10

he c-cmplary embodiment of apparatus depicted in Flt Lu cooperates with an electronic yarn cleaner, which encompasses an electronic evaluation device 1 with three controllable evaluation channels K1, K2, K3, a feeler or scanner head 3 which operates, for instance, optoelectrically and a central control signal transmitter or generator 33. In practice there is provided a single control signal transmitter 33 for a larger group of, for instance, 50 winding stations or locations, each of which is equipped with an evaluation device 1 and feeler or scanner head 3. The evaluation device of each winding station location has delivered thereto from the associated feeler head 3 its electrical scanning signal S via a direct-current voltage signal amplifier DCA, which also can be mounted in or at the feeler head and delivers an amplified scanning signal VS. The feeler head 3 encompasses, for instance, an optoelectrical yarn feeler mechanism 5 which delivers the scanning signal S, and the yarn cutter or separation device 4; such is connected at the output of the evaluation device 1 and is actuated by a cutting or separation pulse T when there travels through the feeler head a non-tolerable yarn defect, especially a yarn thickened location. Upon actuation of the cutter device 3 the yarn or thread is cut, the winding location brought to standstill and a knotting operation initiated, as such is well known in the textile art. After completion of the knotting operation the winding location or station is again placed into operation.

The inventive apparatus encompasses an electronic thickness signal transmitter 2, the input of which is connected to the direct-current voltage amplifier DCA, and the output signal of which, namely the thickness signal, is delivered to the control signal transmitter 33. Thus each group of winding locations of stations has only associated therewith one thickness signal transmitter 2. Therefore, the thickness signal transmitter 2 and the control signal transmitter 33 can be advantageously assembled together into a central control device. Normally the scanning signal S or VS respectively, which is delivered to the thickness signal transmitter 2, is derived from a predetermined winding location or station, the so-called pilot winding station. However, there is also the possibility, during the adjustment operation to derive a scanning signal S or VS by simultaneous formation of the average value in parallel form from a number of winding stations, or however to connect the individual winding stations one after the other with the central control device, so that they are all interrogated in a cyclic sequence and adjusted. There will now be more fully described the construction of the aforementioned circuit blocks 1, 2, 5 and 33.

The optoelectrical yarn feeler device or mechanism 5, in the embodiment under consideration, is designed such that in the case of an empty measuring or measurement field it delivers a base signal which corresponds to the non-shaded light current in the measurement field. The yarn can be scanned with uniform light or with light pulses. If a yarn or the like is introduced into the measurement field, then the light current is shaded and the scanning signal S' or VS respectively is reduced by an amount corresponding to the yarn cross-section. For the purpose of scanning yarns there are well known to the art for quite some time certain uniform light-feeler or scanner devices, for instance of the type disclosed in British Pat. No. 442,811, the disclosure of which is incorporated herein by reference. Modern scanning devices which function with light pulses have been disclosed in the commonly assigned, copending US. applications Ser. No. 377,824, filed July 9, 1973, entitled optoelectrical Apparatus" and 18 Ser. No. 402,187, filed Oct. 1, l973 and also entitled Optoelectrical Apparatus."

The direct-current voltage amplifier DCA coupled with the yarn feeler device 5, which can have a gain or amplification factor of about 100, accordingly during the scanning of a yarn 11 or the like delivers an amplified scanning signal VS, the value of which is that much smaller the greater the thickness of the yarn located at the feeler or scanner head 3.

The electronic evaluation device 1 encompasses three control channels, namely a double yarn channel Kl, a short defect channel K2 and a long defect channel K3, which possess a common output stage T. According to the showing of FIG. 10 there are provided at the control channels K1, K2, K3 the diodes D1, D2, D3 respectively, which are pre-biased in the blocking direction, and with the aid of which there can be controlled the response sensitivity of the evaluation device 1 by means of the control voltages or signals VC, VN, VD which are positive in this case. For all three control channels there is only provided the one amplifier DCA, so that the gain of the scanning signal S is the same for all of these channels. Following the amplifier DCA there is provided at the double yarn channel Kl a lowpass filter TP and a capacitor C1, with which there is coupled the cathode of the diode D1. The anode of such diode D1 is connected with the one input of the output stage T which is constructed as a logic OR- circuit with three inputs and is normally maintained at null potential. The positive control voltage VC from the control signal transmitter 33 is delivered through the agency of a pre-resistor RC to the cathode of the diode D1, so that such is pre-biased in the blocking di rection. In this way there is achieved the result that upon the occurrence of signal pulses at the scanning signal S' or the amplifier signal VS, which arrive via the low-pass filter TP and the capacitor C1 at the cathode of the diode D1, there are only passed to the logic OR-circuit T such signals, the amplitude of which exceeds the control voltage VC. Both of the control channels K2 and K3 are similarly constructed according to the embodiment of FIG. 10, however, without any lowpass filter, and the capacitors C2 and C3 are directly connected with the output of the amplifier DCA. The outputs of such control channels K2 and K3 are connected in each case with one or the other input of the logic OR-circuit T.

In the long defect channel K3 there is further provided between the anode of the diode D3 and the output stage T a length measuring channel LM at which there is compensated the effect of the traveling speed of the yarn upon the measurement of the length of the yarn defect by means of a length signal L, which is tapped-off a manually adjustable potentiometer or can be automatically generated in known manner.

The control signal transmitter or generator 33 contains a respective potentiometer 33C, ISBN, 330 for the adjustment or setting of the control voltages VC, VN, VD of the three control channels K1, K2, K3 of the evaluation device 1. While the one end or terminal of each potentiometer is connected with ground, the other terminals of the three potentiometers are connected in parallel with the output of the thickness signal transmitter 2.

The electronic thickness signal transmitter 2 is connected with the output of the direct-current voltage amplifier DCA. It contains five functional units, namely a subtraction element or subtractor 7, a non-linear transmission element 34, a compensation circuit 9, an integration circuit [4 and a relay switching circuit 32. The compensation circuit 9 is connected with its input at the output of the subtractor 7 and with its output at the positive input thereof, as shown. The negative input of the subtractor 7 has delivered thereto the scanning signal VS which has been amplified at the amplifier DCA, so that there appears at the output of the subtractor 7 a yarn signal F. the magnitude of which varies in the same sense or direction as the transverse dimension of the yarn ll or the like.

The compensation circuit 9 is constructed in the corresponding manner as the same has been illustrated in conjunction with the showing of FIG. 3, however both of the parallel connected work contacts CCl and CC2 are actuated in a different manner. Reference character RA designates a direct-current voltage amplifier stage with high gain of, for instance, 10,000, reference character HCl represents a holding capacitor and ref erence character IS an impedance converter stage with a field-effect transistor as its input. As the output signal K the compensation circuit 9 delivers a DC-voltage of practically the same magnitude as the amplified base signal VS of the empty feeler head 3 which is delivered to the negative input of the subtraction element or subtractor 7.

The integration circuit 14 encompasses an input resistor RV. a holding capacitor HC2 and a linear directcurrent voltage amplifier QA. The time-constant of the RC-element, which consists of the components RV and HC2, brings about a timewise average value formation of the yarn signal F measured during travel of the yarn over a longer yarn section and can amount to, for instance, to 10 seconds. The input resistor RV of the integration circuit 14 can be connected by means of the work contact CH of a relay H of the relay switching circuit 32 via the non-linear transmission means 34 with the output E1 of the subtractor 7. The relay switching circuit 32 contains a rectifier bridge BR, the one diagonal of which has delivered thereto, via a buffer or isolating capacitor CB. the AC- voltage components of amplified scanning signal VS delivered by the amplifier DC'A and at the other diagonal of which there is connected the winding of the relay H.

The non-linear transmission element 34, for instance a logarithmic amplifier, has the function of transmitting large yarn signals F' relative to small yarn signals F with smaller gain. The transmission element 34 is. however, not necessary for the functioning of the thickness signal transmitter 2, therefore can be readily omitted, so that then the yarn signal F is directly delivered to the integration circuit 14.

The mode of operation of the arrangement depicted in FIG. 10 at the start of the operation is as follows:

Initially, without any yarn 11 located in the feeler head 3, after switching-in the current supply to all of the circuits, there is adjusted the threefold value for the adjustment parameters C,., D,.. N,. related to the unit of the yarn thickness and corresponding to the yarn to be monitored, for instance C, 1.4. D, l2 and N, 7. Then the work contact CCl of the compensation circuit 9 is manually closed for a short period of time in order to compensate to null the output signal F of the subtractor 7. The work contact CCl also can be automatically closed with the switching-in of the current supply and again opened prior to starting of the winding station. After opening of the contact CC], insertion of the yarn F in the feeler or sensor head 3 and starting of the pilot winding station, the relay H is energized by the ACvoltage components contained in the amplified output signal VS after rectification in the rectifier bridge BR of the relay switching circuit 32 and the relay contact CH is closed, so that the integrationand storage circuit 14 is connected with the output E1 of the subtractor 7. Now the holding capacitor HC2 is charged to a voltage determined by the yarn signal F with a delay of 5 to [0 seconds in accordance with the time-constant. At the output of the amplifier QA there appears a positive thickness signal Q, the magnitude of which is determined by the yarn signal F and the gain or amplification factor of amplifier QA, which amounts to for instance 10, and which thus is representative of the yarn thickness determined over a longer yarn section.

The function of the non-linear transmission element 34 can be compared with a dynamic compression, wherein yarn signals F at the lower magnitude range are transmitted with a higher gain or amplification factor than yarn signals in the upper magnitude range.

The positive thickness signal Q appears at the potentiometers 33C, 33N, 33D and thus automatically determines the positive control voltages VC, VN, VD, which are tapped-off at such potentiometers, and which regulate the response sensitivity of the control channels K1, K2, K3 in the sense that with an increase of the yarn thickness the response sensitivity is reduced and the response threshold is increased. Consequently, the response thresholds of the control channels K1, K2, K3 are automatically adjusted or set and in the same sense as the timewise determined thickness of a yarn 11 which travels through the feeler or scanner head 3.

Description of FIG. 11

The conditions arising during the adjustment operation and upon occurrence of a yarn defect will be explained in conjunction with FIG. 11, in which the upper graph or diagram portrays the course of the amplified scanning voltage or signal VS and the lower graph the course of the output voltage Q of the thickness signal transmitter 2 and the control voltages VC, VN, VD derived therefrom.

As numerical examples for the magnitudes of the mentioned signals and the control voltages there have been assumed, by way of example, the following: The amplification or gain of the output signal Q in relation to the amplified scanning signal VS in the thickness signal transmitter 2 amounts to 10. The adjustment device 33C of the double yarn channel K1 is adjusted to the value C l.4, the adjustment device 33N of the short defect channel K2 to the value N 7 and the adjustment device 33D of the long defect channel K3 to the value D, [.2.

With an empty measurement field at the feeler head 3 there is present the constant base signal VG. The associated thickness signal Q after compensation of the base signal in the circuit 9-- is equal to null.

Now at the point in time A a yarn is introduced into the feeler head 3 and is moved through the feeler head at a speed corresponding to the winding speed. The signal VS upon insertion of the yarn, drops by the amount F, which corresponds to a uniform thickness of the yarn. The thickness signal Q reaches its final value, which corresponds to the value of F, only after a longer time of, for instance 20, seconds at the point B. The three control signals, beginning from point A, increase uniformly or in the same sense with the signal Q, however reach their final value somewhat at point C owing to the delay which is additionally brought about by the time-constants of the elements RC C1, RN C2, RD C3. In order to avoid erroneous cuts the cutter device 4 can be blocked during the starting phase up to point B or point C.

Now there occurs at point D a thickened location of uniform cross-section in the measurement field. Consequently, the signal VS drops further during a duration of, for instance, IO milliseconds by the amount F". For the sake of clarity in illustration the interval between the beginning D and the end E of the error or defect signal has been shown markedly elongated in the upper graph of FIG. 2 in contrast to the interval AD. Let it be assumed that the ratio F '/F amounts to l corresponding to a doubling of the yarn diameter. This means however that the diameter of the thickened location, related to the normal value of the diameter represented by the value F', has the value 2. If for instance F 1 volt, then Q volts, VN 6 volts, VC 0.4 volts and VD 0.2 volts (the corresponding curves for C, and D,- have been shown on an over enlarged scale in relation to N, in FIG. 11 for the purpose of improving clarity in illustration). Since in the assumed situation also F" 1 volt, both the channel Kl as well as also the channel K3 are brought to respond, not however the channel K2. The indicated value for VN can be calculated from the equation and the same is correspondingly applicable for VC and VD.

Since the length of the thickened location is only slight and corresponds to a throughpassage time of 10 milliseconds, its throughpassage has practically no effect upon the thickness signal Q.

The automatically brought about adjustment of the channels of the evaluation device remains until the occurrence of a considerable defect (as has just been assumed), by means of which there is initiated a cutting of the yarn and standstill of the winding location, or until depletion of the yarn supply at the delivery bobbin or spool, also known as delivery cop. Upon actuation of the yarn cutter device 4 by a cutting pulse T there is also closed the work contact CC2 and owing to absence of the yarn in the measuring field following the cutting operation the relay H is deenergized and its contact Cl-I is opened. Prior to insertion of the yarn the contact CC2 is automatically again opened. After completion of the knotting operation and restarting of the winding location or station again the contact CH of the relay H is closed, with the result that the operation begins anew. A corresponding operation occurs during changing of the cop or spool.

There will be recognized from this description that the compensation of the base signal VG which exists for the empty feeler head 3 is always carried out in the short intervals of the exchange of the delivery cop or the knotting operation; the compensation signal K which is set or adjusted in one such interval at the output of the compensation stage 9 remains practically unchanged after opening of the contact CC2 owing to the storage effect of the components I-ICl and IS. This mode of operation however presupposes that the influence of the drift of the base signal upon the output signal Q in the time period between two such intervals, which is in the order of magnitude of a few minutes, is practically equal to null, i.e., must be considerably smaller than the value of the output signal 0, in order to obtain exact results. Therefore there are placed un usually high requirements upon the stability of the amplified scanning signal VS, which cannot be fulfilled with known yarn cleaners. One of these requirements concerning the longtime stability, however, can be realized by means of an optoelectrical yarn cleaner with a regulation channel as has been illustrated and described in the previously mentioned commonly assigned, copending US. application, Ser. No. 402,187, filed Oct. 1, l973, the disclosure of which is incorporated herein by reference.

According to a variant of the described apparatus it is possible to use a yarn feeler device or scanner which delivers a scanning signal S', the magnitude of which, right from the start, is in the same sense and preferably proportional to the thickness of the scanned yarn, so that there is no longer necessary a compensation circuit 9. An apparatus suitable for this purpose has been dis- I closed, for instance, in US. Pat. No. 2,565,500, inc0r porated herein by reference; in such patent there is provided a conventional scanning of feeler device with two photoelectric cells which are connected back-toback. With such apparatus it is possible to compensate to null the base signal which appears in the case of an empty feeler head, so that with the yarn inserted there is formed a scanning signal which is approximately proportional to the yarn thickness. In practice it is of course hardly possible to maintain such compensation over a longer time, since with the present day state of this technology it has not yet been possible to mass produce optoelectrical transducers, the sensitivity of which, during temperature changes and aging, alters in a completely similar relationship. A scanning device which can be used in practice, which delivers a compensated, sufficiently stable scanning signal proportional to the yarn diameter has, however, been disclosed in the previously mentioned commonly assigned, copending US. application, Ser. No. 377,824, filed July 9, I973, and incorporated herein by refer ence. As mentioned, when using such yarn scanning device, at which there occurs a compensation of the scanning signal S which is present with the feeler head 3 empty, already at the optical system of the feeler or scanning head, there can be dispensed with any special compensation circuit 9.

Description of FIG. 12

The electronic yarn cleaner depicted in FIG. 12, like the arrangement shown in FIG. 10, embodies an electronic evaluation device I, a feeler or scanner head 3 and a control signal transmitter 33. The evaluation device and the control signal transmitter 33 can be constructed in the same manner as such has already been described in conjunction with the system of FIG. 10. In this case, however, what is different is the yarn feeler device 5A and a signal processing circuit SPC which is connected therewith. This signal processing circuit SPC is used in place of the direct-current voltage amplifier DCA of the arrangement of FIG. 10 and delivers an amplified scanning signal VS which is free of a base signal generated with the empty feeler head. In other words, the signal VS, in this case, directly represents 

1. A method for adjusting an electronic yarn cleaner which embodies a yarn feeler for generating a scanning signal dependent upon the cross-section of a yarn to be cleaned and at least one controllable channel connected with the yarn feeler for evaluating the scanning signal and for triggering a yarn cutting device when there is present a defective cross-section of the yarn, the improvement comprising the steps of: deriving from the scanning signal, during running of the yarn, a thickness signal, the magnitude of which is representative of the yarn thickness determined over a longer yarn section, for the purpose of automatically adjusting at least one evaluation channel, and feeding the thickness signal defining a control signal or a signal derived therefrom defining a control signal to the evaluation channel in order to be able to adjust its response threshold in the same sense as the magnitude of the thickness signal.
 2. The method as defined in claim 1, for adjusting an electronic yarn cleaner with a number of controllable evaluation channels, wherein derivation of the control signals intendEd for the evaluation channels and the delivery thereof to the evaluation channels occurs in successive time intervals.
 3. The method as defined in claim 1, for adjusting an electronic yarn cleaner with a number of controllable evaluation channels, wherein the derivation of the control signals intended for the individual evaluation channels and the delivery thereof to the evaluation channels occurs simultaneously and parallel to one another in separate channels.
 4. The method as defined in claim 1, for adjusting an electronic yarn cleaner with a number of controllable evaluation channels, wherein the derivation of the control signals intended for the individual evaluation channels occurs simultaneously by simultaneously forming from the thickness signal and signals which represent the relative cleaning boundaries of the evaluation channels, the control signals for all evaluation channels.
 5. The method as defined in claim 1, for adjusting an electronic yarn cleaner with a number of controllable evaluation channels, wherein derivation of the control signals intended for the individual channels occurs simultaneously from the thickness signal by voltage division as a function of the relative cleaning boundaries of the evaluation channels.
 6. The method as defined in claim 1, for adjusting an electronic yarn cleaner which, without yarn present at the yarn feeler, delivers a base signal differing from null, and with a yarn located in the yarn feeler mechanism generates a scanning signal which differs from the base signal by an amount substantially corresponding to the cross-section of the yarn, further comprising the steps of compensating the base signal so that there is formed a yarn signal representative of the cross-section of the yarn, and deriving from such yarn signal the thickness signal by carrying out an integration of such yarn signal as a function of time.
 7. The method as defined in claim 1, for adjusting an electronic yarn cleaner which directly delivers a yarn signal representative of the thickness of the yarn, further comprising the steps of transforming such yarn signal into the thickness signal while determining such yarn signal over a longer yarn section.
 8. The method as defined in claim 7, further including the step of amplifying the yarn signal which is transformed into the thickness signal.
 9. An apparatus for adjusting an electronic yarn cleaner comprising a yarn feeler, an electronic evaluation device connected with the yarn feeler, said electronic evaluation device possessing at least one controllable evaluation channel having a control input and serving for triggering a yarn cutter mechanism in the event of a defective cross-section of a yarn which is to be cleaned, electronic means for the integration as a function of time of a yarn signal which characterizes a local transverse dimension of a section of the yarn located in the yarn feeler of the yarn cleaner for generating a thickness signal, the magnitude of which thickness signal is representative of the cross-section of the yarn determined over a longer yarn section with the yarn traveling, said electronic means having an output operatively connectable with said control input.
 10. The apparatus as defined in claim 9, for use with an electronic yarn cleaner in which a yarn scanning signal generated by the yarn feeler is present as a DC-voltage signal and is amplified in the manner of an AC-voltage, a controllable DC-amplifier channel to which there is delivered to yarn scanning signal derived from the yarn feeler and which contains a base signal, and a compensation device cooperating with the DC-amplifier channel for suppressing the base signal.
 11. The apparatus as defined in claim 10, wherein the compensation device is constructed as a feedback circuit having a feedback loop of the DC-amplifier channel, said feedback circuit including switching means in order to activate from time to time the feedback circuit for compensation of the yarn scanning siGnal, and means for holding a compensation signal which appears when the feedback loop of the feedback circuit is closed.
 12. The apparatus as defined in claim 11, wherein the feedback circuit is normally interrupted, and further including null adjustment means for automatically closing the normally interrupted feedback circuit when placing into operation the apparatus and during removal of a yarn out of the yarn feeler.
 13. The apparatus as defined in claim 11, wherein said DC-amplifier channel has an output, said electronic integration means including an integration- and storage circuit coupled with the output of the DC-amplifier channel in order to form from the output signal of the DC-amplifier channel defining said yarn signal the thickness signal and to store such thickness signal during the intervals when the yarn is removed out of the yarn feeler and the compensation device is effective.
 14. The apparatus as defined in claim 9, further including a switching circuit which, with the yarn traveling, is actuated by a scanning signal derived from the yarn feeler and thereby activates the electronic means for the integration of the yarn signal.
 15. The apparatus as defined in claim 9, further including a servo circuit incorporating a comparator having a pair of inputs and an output, the thickness signal being delivered to one input of the comparator, a potentiometer having a tap, means for applying a constant voltage to the potentiometer, said tap being coupled with the other input of the comparator, a reversible adjustment motor which can be connected with the output of the comparator and acting upon the potentiometer tap, and wherein the thickness signal, after balancing of the input signal of the comparator, appears in the form of a constant DC-voltage at the tap of the potentiometer.
 16. The apparatus as defined in claim 9, for use at an electronic yarn cleaner with a number of controllable evaluation channels, comprising an electronic thickness signal transmitter embodying electronic means for amplifying and integrating as a function of time a scanning signal delivered thereto and for generating therefrom the thickness signal, and further including a control signal transmitter, said control signal transmitter including means for adjusting relative cleaning boundaries of the individual evaluation channels and forming from the thickness signal and the adjusted values of the cleaning boundaries control signals for the evaluation channels.
 17. The apparatus as defined in claim 16, wherein said means of the control signal transmitter comprise adjustable voltage dividers. 